For the steady laminar helical flow of incompressible viscous liquid, the component of curl is a harmonic function, and the existence of a potential function for the curl of second order may be expected. 不可压缩粘性液体的恒定螺旋层流,旋度分量必是调和函数,二阶旋度必有势函数,并有相应的能量方程;